Economy liquidtight fitting

ABSTRACT

A fitting for a liquidtight conduit that includes a compression ring, a ground cone and a locknut. The compression ring has a first end that is adapted to receive a liquidtight conduit and a second end that has a perimetrical lip that extends radially from the exterior surface and a collar that extends from the second end. The locknut is ring-shaped and has an aperture in the middle. The ground cone has a flanged end and a plain end. The locknut passes over the plain end and is attached to the back side of the flanged end. When the fitting is installed, the plain end of the ground cone passes through an aperture in a wall and the second end of the compression ring. A plurality of threads on the exterior surface of the ground cone engages the interior surface of the liquidtight conduit in the compression ring and, when the ground cone is rotated, the threads move the conduit towards wall.

This application claims priority from provisional application Ser. No.61/195,423, filed on Oct. 7, 2008, which is incorporated herein in itsentirety.

FIELD OF THE INVENTION

The present invention is a fitting for quickly connecting anddisconnecting liquidtight conduit. In particular, the present inventionrelates to an electrical fitting that is used to connect liquidtightconduit to the wall of an enclosure.

BACKGROUND OF INVENTION

Liquidtight flexible conduit is used in many applications, includingindustrial applications, to protect electric current-carrying wires. Thefittings presently being used to connect liquidtight conduit toenclosures include multiple components and are expensive to manufacture.Accordingly, there is a need for an economical fitting that can beeasily installed and provides a reliable liquidtight seal with highconduit pull-out resistance. There is also a need for a fitting forattaching a conduit to an enclosure that can be tightened either by handor with tools.

SUMMARY OF THE INVENTION

In accordance with the present invention, a liquidtight fitting isprovided that includes a compression ring, a ground cone and a locknut.The compression ring includes a tubular body, a perimetrical lip, acollar and a stop. The tubular body has an interior surface, an exteriorsurface, an inner diameter, a first end and a second end. The first endis adapted to receive a liquidtight conduit having an interior surface.The perimetrical lip extends radially from the exterior surface near thesecond end of the tubular body and the collar is connected to andextends from the second end of the body. The collar is ring-shaped andthe side of the collar opposite the second end of the tubular body has adistal circumferential edge. Preferably, the collar has an innerdiameter that is less than the inner diameter of the tubular body of thecompression ring. The stop is located on the interior surface of thebody and is adapted to prevent the conduit from passing through thesecond end of the tubular body. Preferably, the stop is formed at thepoint where the collar connects to the second end of the tubular body.The compression ring can also include an O-ring extending radiallyinwardly from the interior surface and intermediate the first and secondends of the tubular body. The O-ring has an inner diameter that is lessthan the inner diameter of the tubular body and sealably receives theliquidtight conduit inserted into the first end of the compression ring.

The ground cone includes a cylindrical body, a plain end and a flangedend. The cylindrical body has an axial bore, an inner surface, an outersurface, an outer diameter and a plurality of threads on the outersurface. The plain end is adapted to be inserted into the second end ofthe compression ring and the threads are adapted to engage the interiorsurface of the liquidtight conduit that is inserted into the first endof the compression ring. When the ground cone is rotated, the threadsmove the conduit towards the second end of the compression ring in ascrew-like manner. The flanged end of the ground cone has a front flangesurface opposite the plain end and an opposing back flange surface.

The locknut includes a substantially flat ring-shaped body having afirst side, a second side, an inner diameter and an outer diameter.Preferably, the inner diameter of the locknut is greater than the outerdiameter of the cylindrical body of the ground cone. The first end ofthe ground cone is inserted through the locknut and the first side ofthe locknut is attached to the back flange surface of the ground cone.The ring shaped body of the locknut has an inner circumferential edgeand an outer circumferential edge. The outer circumferential edge canhave a plurality of flat surfaces that are adapted for engagement by awrench. Preferably, the inner circumferential edge is tapered so thatthe diameter of the inner circumferential edge on the first side is lessthan the diameter of the inner circumferential edge on the second sideof the locknut. The second side of the locknut can have a plurality ofgrooves extending between the inner and outer circumferential edges.These grooves engage the flat surface of a wall or enclosure when theliquidtight fitting is installed.

To install the fitting, the liquidtight conduit is inserted into thefirst end of the compression ring and the plain end of the ground coneis inserted into an opening in a flat surface, typically a wall, andthen into the second end of the compression ring. The ground cone andthe locknut are rotated so that the threads on the outer surface of theground cone engage the interior surface of the liquidtight conduit andmove the conduit towards the flanged end of the ground cone. At the sametime, the distal circumferential edge of the collar is sealably receivedby the inner circumferential edge of the locknut and the perimetricallip sealably contacts the flat surface.

In a preferred embodiment, the ground cone and the locknut are formed asa unitary structure. This combination of the ground cone and locknut isalso referred to herein as the ground cone/locknut assembly. Thecompression ring is preferably made from a semi-rigid material, such asan elastomeric material. The material must be rigid enough to maintainits shape and pliant enough so that it forms a seal around theliquidtight conduit and against the wall when the fitting is tightened.As used herein, the term “elastomeric material” refers to athermoplastic or thermoset material that can stretch and then return toits original shape without permanent deformation, such as rubber orcertain types of plastic materials. The ground cone and locknut can bemade from either a metal material or a combination of metal and plastic.

BRIEF DESCRIPTION OF THE FIGURES

The preferred embodiments of the liquidtight fitting of the presentinvention, as well as other objects, features and advantages of thisinvention, will be apparent from the accompanying drawings wherein:

FIG. 1 is a side, sectional view of the liquidtight fitting mounted tothe wall of an enclosure.

FIG. 2 is a side, sectional view of the ground cone/locknut assembly ofthe liquidtight fitting shown in FIG. 1.

FIG. 3 is a side, sectional view of the compression ring of theliquidtight fitting shown in FIG. 1.

FIG. 4 is an end view of the flanged surface of the ground cone shown inFIG. 2.

FIG. 5 is a side view of the locknut shown in FIG. 2.

FIG. 6 is an end view of the locknut shown in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a fitting that is used to connectinsulated cables or conduits (also referred to herein as “liquidtightconduit”) to a flat surface such as a wall of an enclosure. The fittingsare designed to maintain the liquidtight integrity of the conduit at thepoint where the conduit is connected to the enclosure. Similar fittingsare disclosed in U.S. Pat. No. 5,072,072 to Bawa et al. and U.S. Pat.No. 7,183,486 to Pyron et al., both of which are incorporated herein intheir entirety.

The liquidtight fitting of the present invention includes a locknut thatis attached to a ground cone and can be formed as a unitary structure.The locknut/ground cone assembly is inserted through an opening in asubstantially flat surface (also referred to herein interchangeably as“a wall” or “the wall of an enclosure”) from the inside so that the stopsurface (i.e., the flat surface of the locknut) contacts the surface ofthe wall around the opening on the inside of the enclosure and preventsthe locknut/ground cone assembly from passing through to the outside. Toaccomplish this, the diameter of the aperture of the locknut is at leastabout the same as the diameter of the opening in the wall and the outerdiameter of the ring-shaped locknut is greater than the diameter of theopening in the wall. The ground cone portion operates in the normalfashion (i.e., it electrically contacts the liquidtight conduit toground the conduit to the inside of the enclosure) and is threaded intothe inside of an insulated cable or conduit. On the outside of theenclosure, one end of the compression ring is fitted onto the end of aliquidtight conduit (a stop inside the compression ring limits theinsertion distance). The second end of the compression ring is thenpushed onto the ground cone so that the ground cone is positioned insidethe liquidtight conduit. As the ground cone is rotated, it draws theliquidtight conduit towards the wall of the enclosure, thereby causingthe second end of the compression ring to abut the enclosure and form aseal around the opening in the wall of the enclosure.

As used herein, the term “liquidtight conduit” refers to different typesof flame-resistant, non-metallic tubing with interior surfaces that canbe smooth or corrugated. The liquidtight conduit can have integralreinforcement within the conduit wall. However, the use of the term“liquidtight conduit” is not intended to limit the scope of theinvention and the fitting can be used with other types of insulatedcables and conduits.

The locknut/ground cone assembly is formed by passing a locknut over theplain end of a ground cone and then affixing it to the back surface ofthe flange on the second end of the ground cone (or, alternatively,forming the two components as an integral unit, i.e., a unitarystructure). The locknut/ground cone assembly is inserted into one sideof an opening in a wall (generally the interior side of an enclosure)and then into the compression ring as described in more detail below.The opening is sized so that the flat surface of the locknut extendsbeyond the perimeter of the opening and prevents the locknut/ground coneassembly from being pulled through the opening when the fitting istightened.

The ground cone has a cylindrical body with an axial bore, an innersurface, an outer surface, an outer diameter and a plurality of rings orthreads on the outer surface. The ground cone also has a plain endadapted for insertion into the second end of the compression ring and aflanged end having a front flange surface opposite the plain end and aback flange surface. The threads on the outer surface of the cylindricalbody are adapted to engage the interior surface of a liquidtight conduitand, when rotated, draw the conduit and the compression ring towards theflanged end of the ground cone.

The locknut has a substantially flat ring shaped body with an innerdiameter and an outer diameter. The inner diameter is greater than theouter diameter of the cylindrical body of the ground cone. Thering-shaped body of the locknut has an inner circumferential edge thatis tapered or beveled so that the inner circumferential edge on thefirst side (i.e., the side that contacts the flanged end of the groundcone when the locknut is attached to the ground cone) has a smallerdiameter than the inner circumferential edge on the second side (i.e.,the side that contacts the wall of the enclosure) of the locknut. Thisallows the collar of the compression ring to snugly fit into the annularspace between the circumferential edge of the locknut and the groundcone. When the fitting is tightened, the distal circumferential edge ofthe collar sealably contacts the ground cone and locknut. The secondside of the locknut can have a plurality of grooves extending betweenthe inner and outer circumferential edges. These grooves provide agriping surface when the locknut is tightened against the wall of anenclosure.

The cylindrically shaped compression ring has a tubular-shaped body, anaxial bore extending between the first and second ends, a first innerdiameter, an interior surface and an exterior surface. The first end ofthe compression ring receives a liquidtight conduit and the second endreceives the plain end of the ground cone. The second end of thecompression ring has a perimetrical lip extending radially from theexterior surface and a ring-shaped collar extending from the second end.The collar operates as described above and the perimetrical lip sealablycontacts the wall of the enclosure when the fitting is tightened duringinstallation.

The end of a liquidtight conduit is inserted in the first end of thecompression ring and pushed in until the conduit is prevented frommoving any further by a stop on the interior surface of the compressionring near the second end. This stop can be formed by the collar.Preferably, the collar has an inner diameter that is less than the innerdiameter of the tubular-shaped body of the compression ring. The pointon the inner surface of the compression ring where the inner diameter isreduced is designed so that the liquidtight conduit cannot pass throughthe second end of the compression fitting.

After the locknut/ground cone assembly is inserted through the openingin a wall, the plain end of the ground cone is inserted into the secondend of the compression ring and then into the bore of the conduit. Theassembly is rotated to draw the conduit and compression ring toward thewall of the enclosure. This causes the compression ring to ultimatelysealably contact the outside surface of the enclosure. A seal is alsoformed on the inside of the compression ring by an O-ring that extendsradially inwardly from the interior surface of the compression ring at apoint intermediate the first and second ends. The O-ring is compressibleand the inner diameter is designed to snugly engage the liquidtightconduit. When a liquidtight conduit is inserted in the compression ring,the O-ring provides a seal to prevent dust and moisture from entering.

When the fitting is used to attach a liquidtight conduit to a flatsurface, such as the wall of an enclosure, the liquidtight conduit isinserted into the first end of the compression ring up to the stop onthe inside of the compression ring adjacent the collar. The plain end ofthe ground cone is inserted into an opening in the flat surface and theninto the second end of the compression ring. The ground cone and thelocknut are rotated so that the threads on the outer surface of theground cone engage the interior surface of the liquidtight conduit. Thisdraws the compression ring and liquidtight conduit towards the flatsurface until the collar of the compression is snugly contacting theflat surface.

Referring now to the drawings, FIG. 1 shows the liquidtight fitting 10mounted to the wall 50 of an enclosure and connected to a liquidtightconduit 52. The flanged end 26 of the ground cone 14 is attached to (orformed as part of) the locknut 24 to create the ground cone/locknutassembly 12. Plain end 16 of the ground cone 14 is then inserted throughthe wall 50 of the enclosure from the inside. A liquidtight conduit 52having interlocked, inner steel body 56 and an outer jacket 54 isinserted into the first end 32 of the compression ring 30 until it abutsstop 39. The second end 34 of the compression ring 30 is pushed over theplain end 16 of the ground cone 14. The ground cone/locknut assembly 12is then rotated so that the threads 17 on the exterior surface of thecylindrical body 18 of the ground cone 14 engage the interior wall 58 ofthe liquidtight conduit 52 to draw the conduit 52 along with thecompression ring 30 towards the wall 50. The ground cone/locknutassembly 12 is rotated until the collar 40 on the second end 34 of thecompression ring 30 passes through the opening in the wall 50 and theperimetrical lip 42 is flush against the exterior of the wall 50.

FIG. 2 shows the ground cone/locknut assembly 12 of the liquidtightfitting 10, which is formed when the ground cone 14 is attached to thelocknut 24. The ground cone 14 has a cylindrical body 18 with aplurality of threads 17 on the exterior surface, a flanged end 26, aplain end 16 and an axial bore 25 extending between the two ends 16, 26.The locknut 24 is substantially flat and ring-shaped with an outercircumferential edge 21, an inner circumferential edge 23, a first side27 and a second side 29. The locknut 24 receives the plain end 16 and ismoved over the cylindrical body 18 until the first side 27 of thelocknut 24 abuts the back surface 20 of the flanged end 26 of the groundcone 14. The first side 27 of the locknut 24 is then attached to theback surface 20 of the flanged end 26 using fasteners, an adhesive,welding, or other means to form the ground cone/locknut assembly 12. Themethod used to attach the ground cone 14 to the locknut 24 depends onthe materials that are used to fabricate the components. The second side29 of the locknut 24 contacts the inside wall 50 of a flat surface whenthe fitting 10 is installed. Alternatively, the ground cone/locknutassembly 12 may be formed as a unitary structure. The flanged end 26 ofthe ground cone 14 has a plurality of apertures 22 that can be used toattach the locknut 24. The locknut 24 also serves as a stand-off tospace the flanged end 26 of the ground cone 14 away from the surface ofthe wall 50. This creates a gap which is sealed by the collar 40 whenthe fitting 10 is installed in the wall 50 and tightened.

FIG. 3 shows the compression ring 30 component of the liquidtightfitting 10 with a first end 32 for receiving a liquidtight conduit 52(FIG. 1), a smaller diameter second end 34 for receiving the plain end16 of the ground cone 14 and an axial bore 35 extending between the twoends 32, 34. The exterior surface 36 of the compression ring extendsradially outwardly between the first end 32 and the second end 34. Thefirst end 32 is sized to compressively receive the liquidtight conduit52. The second end 34 is sized to receive the ground cone/locknutassembly 12 and has a perimetrical lip 42 that extends radiallyoutwardly from a point between a collar 40 and the second end 34 of thecompression ring 30. The compression ring 30 has an O-ring 38 extendinginwardly from the interior surface 37 that is located intermediate thetwo ends 32, 34. The step or stop 39 near the second end of thecompression ring 30 limits how far the liquidtight conduit 52 can beinserted into the compression ring 30 before the ground cone/locknutassembly 12 is connected to the compression ring 30. When the groundcone/locknut assembly 12 is rotated, the conduit 52 is drawn towards thesecond end 32 of the ground cone 14. The collar 40 extends from thesecond end 34 and is flexibly attached thereto. When the groundcone/locknut assembly 12 is inserted into a liquidtight conduit 52installed in the compression ring 30 and tightened, the collar 40 isdrawn through the wall 50 and forms a seal around the innercircumferential edge 23 of the locknut 24. This also sealably compressesthe perimetrical lip 42 against the exterior surface of the wall 50.

FIG. 4 shows an end view of the ground cone/locknut assembly 12 and theflanged end 26 of the ground cone 14. The flanged end 26 has a pluralityof apertures 22 that are used to attach the ground cone 14 to thelocknut 24. The axial bore 25 of the ground cone 14 extends through thecenter of the flanged end 26 and between the opposing ends 16, 26 of theground cone 14. The locknut 24 can have a plurality of flats 19 on itsouter circumferential edge 21 that can be engaged by a wrench fortightening the ground cone/locknut assembly 12.

FIG. 5 is a sectional, side view of the locknut 24 shown in FIG. 2. Thesecond side 29 of the locknut 24 opposite the flanged end 26 of theground cone 14 has a plurality of grooves 28 which are used to grip thesurface of the wall 50 (FIG. 1). FIG. 6 is a view of the second side 29of the locknut 24 shown in FIG. 2 between the first and secondcircumferential edges 21, 23. FIG. 6 shows the grooves 28 in the secondside 29 of the locknut 24 extending between the first and secondcircumferential edges 21, 23 of the locknut 24.

Thus, while there have been described the preferred embodiments of thepresent invention, those skilled in the art will realize that otherembodiments can be made without departing from the spirit of theinvention, and it is intended to include all such further modificationsand changes as come within the true scope of the claims set forthherein.

1. A liquidtight fitting comprising: a compression ring comprising: atubular body having an interior surface, an exterior surface, an innerdiameter, a first end and a second end, wherein the first end is adaptedto receive a liquidtight conduit having an interior surface; aperimetrical lip extending radially from the exterior surface near thesecond end; a collar extending from the second end; and a stop, whereinthe stop is adapted to prevent the conduit from passing through thesecond end of the tubular body; a ground cone comprising: a cylindricalbody having an axial bore, an inner surface, an outer surface, an outerdiameter and a plurality of threads on the outer surface, wherein thethreads are adapted to engage the interior surface of the liquidtightconduit; a plain end adapted for insertion into the second end of thecompression ring; and a flanged end having a back flange surface; and alocknut comprising a substantially flat ring shaped body having a firstside, a second side, an inner diameter and an outer diameter, whereinthe first side of the locknut is attached to the back flange surface ofthe ground cone, wherein the liquidtight conduit is inserted into thefirst end of the compression ring, wherein the plain end of the groundcone is inserted into an opening in a flat surface and then into thesecond end of the compression ring, and wherein the threads on the outersurface of the ground cone are adapted to engage the interior surface ofthe liquidtight conduit when the ground cone and the locknut arerotated.
 2. The liquidtight fitting according to claim 1, wherein theinner diameter of the locknut is greater than the outer diameter of thecylindrical body of the ground cone.
 3. The liquidtight fittingaccording to claim 1, wherein the collar has an inner diameter, andwherein the inner diameter of the collar is less than the inner diameterof the tubular body of the compression ring.
 4. The liquidtight fittingaccording to claim 1, wherein the compression ring further comprises anO-ring extending radially inwardly from the interior surface andintermediate the first and second ends of the tubular body.
 5. Theliquidtight fitting according to claim 1, wherein ring-shaped body ofthe locknut has an outer circumferential edge, and wherein the outercircumferential edge has a plurality of flat surfaces that are adaptedfor engagement by a wrench.
 6. The liquidtight fitting according toclaim 1, wherein the ring shaped body of the locknut has an innercircumferential edge and an outer circumferential edge, and wherein thesecond side of the locknut has a plurality of grooves extending betweenthe inner and outer circumferential edges.
 7. The liquidtight fittingaccording to claim 1, wherein the locknut has an inner circumferentialedge, wherein the inner circumferential edge is tapered so that thediameter of inner circumferential edge on the first side is less thanthe diameter of the inner circumferential edge on the second side. 8.The liquidtight fitting according to claim 7, wherein the collar isring-shaped and has a distal circumferential edge, wherein the innercircumferential edge of the locknut is adapted to sealably receive thedistal circumferential edge when the ground cone and the locknut arerotated and engage the interior surface of the liquidtight conduit. 9.The liquidtight fitting according to claim 1, wherein the perimetricallip is adapted to sealably contact the flat surface when the ground coneand the locknut are rotated.
 10. The liquidtight fitting according toclaim 1, wherein the ground cone and the locknut are a unitarystructure.
 11. The liquidtight fitting according to claim 1, wherein thethreads on the outer surface of the ground cone are adapted to move theliquidtight conduit towards the flanged end of the ground cone when theground cone and the locknut are rotated.
 12. The liquidtight fittingaccording to claim 1, wherein the compression ring is made from anelastomeric material.
 13. The liquidtight fitting according to claim 1,wherein the compression ring is made from a semi-rigid material.
 14. Aliquidtight fitting comprising: a compression ring comprising: a tubularbody having an interior surface, an exterior surface, an inner diameter,a first end and a second end, wherein the first end is adapted toreceive a liquidtight conduit having an interior surface; a perimetricallip extending radially from the exterior surface near the second end; acollar extending from the second end of the body, wherein the collar isring-shaped and has a distal circumferential edge; a stop, wherein thestop is adapted to prevent the conduit from passing through the secondend of the tubular body; and an O-ring extending radially inwardly fromthe interior surface and intermediate the first and second ends of thetubular body; a ground cone comprising: a cylindrical body having anaxial bore, an inner surface, an outer surface, an outer diameter and aplurality of threads on the outer surface, wherein the threads areadapted to engage the interior surface of the liquidtight conduit; aplain end adapted for insertion into the second end of the compressionring; and a flanged end having a back flange surface; and a locknutcomprising: a substantially flat ring shaped body having a first side asecond side, an inner diameter and an outer diameter, wherein the firstside of the locknut is attached to the back flange surface of the groundcon; and an inner circumferential edge, wherein the innercircumferential edge is tapered so that the diameter of innercircumferential edge on the first side is less than the diameter of theinner circumferential edge on the second side, wherein the innercircumferential edge of the locknut is adapted to sealably receive thedistal circumferential edge of the collar, wherein the liquidtightconduit is inserted into the first end of the compression ring, whereinthe plain end of the ground cone is inserted into an opening in a flatsurface and then into the second end of the compression ring, andwherein the threads on the outer surface of the ground cone are adaptedto engage the interior surface of the liquidtight conduit when theground cone and the locknut are rotated.
 15. The liquidtight fittingaccording to claim 14, wherein the compression ring is made from anelastomeric material.
 16. The liquidtight fitting according to claim 14,wherein the collar has an inner diameter, and wherein the inner diameterof the collar is less than the inner diameter of the tubular body of thecompression ring.
 17. The liquidtight fitting according to claim 14,wherein the compression ring further comprises an O-ring extendingradially inwardly from the interior surface and intermediate the firstand second ends of the tubular body.
 18. The liquidtight fittingaccording to claim 14, wherein the perimetrical lip is adapted tosealably contact the flat surface when the ground cone and the locknutare rotated.
 19. A liquidtight fitting comprising: a compression ringcomprising: a tubular body having an interior surface, an exteriorsurface, an inner diameter, a first end and a second end, wherein thefirst end is adapted to receive a liquidtight conduit having an interiorsurface; a perimetrical lip extending radially from the exterior surfacenear the second end; a collar extending from the second end of the body,wherein the collar is ring-shaped and has a distal circumferential edgeand wherein the collar has an inner diameter that is less than the innerdiameter of the tubular body of the compression ring; and an O-ringextending radially inwardly from the interior surface and intermediatethe first and second ends of the tubular body; a ground cone comprising:a cylindrical body having an axial bore, an inner surface, an outersurface, an outer diameter and a plurality of threads on the outersurface, wherein the threads are adapted to engage the interior surfaceof the liquidtight conduit; a plain end adapted for insertion into thesecond end of the compression ring; and a flanged end having a backflange surface; and a locknut comprising: a substantially flat ringshaped body having a first side a second side, an inner diameter and anouter diameter, wherein the first side of the locknut is attached to theback flange surface of the ground con; and an inner circumferentialedge, wherein the inner circumferential edge is tapered so that thediameter of inner circumferential edge on the first side is less thanthe diameter of the inner circumferential edge on the second side,wherein the inner circumferential edge of the locknut is adapted tosealably receive the distal circumferential edge of the collar, whereinthe ground cone and the locknut are a unitary structure, wherein theliquidtight conduit is inserted into the first end of the compressionring, wherein the plain end of the ground cone is inserted into anopening in a flat surface and then into the second end of thecompression ring, and wherein the threads on the outer surface of theground cone are adapted to engage the interior surface of theliquidtight conduit when the ground cone and the locknut are rotated.20. The liquidtight fitting according to claim 19, wherein thecompression ring is made from an elastomeric material.